1. Field of the Invention
The present invention relates, in general, to a method and apparatus for controlling an output voltage and, more particularly, to a method and apparatus for controlling an output voltage by varying a gain of an output voltage controller based on the current-continuity of an inductor in a boost circuit of a direct current-direct current (DC-DC) converter.
2. Description of the Related Art
Generally, a DC-DC converter used in an eco-friendly vehicle has a different control band according to a change in conditions of a high-voltage battery and electronic loads. When the control band is decreased, noise control is substantially high, but the responsiveness is deteriorated, resulting in degradation of the control performance in a transient state. Therefore, a DC-DC converter requires the same control band that extends over the whole operation region without the degradation of responsiveness even when conditions of a high-voltage battery and electronic loads change. The DC-DC converter may consist of a boost circuit having variable activity level and a full bridge circuit having a fixed activity level. An input terminal of the DC-DC converter is connected to the high-voltage battery; and an output terminal of the DC-DC converter is connected to a low-voltage battery and various other electronic loads.
In order to have the same control band inclusive of the whole operation region, an inductor in a boost circuit requires substantially high inductance. When the inductance is sufficiently high, the discontinuity of the current flowing through the inductor of the boost circuit which performs variable activity control may be reduced. However, a problem exists in hardware which cannot sufficiently increase the inductance of the inductor.
The foregoing is intended merely to aid in the understanding of the background of the present invention, and is not intended to mean that the present invention falls within the purview of the related art that is already known to those skilled in the art.